Re: [PATCH v1] perf build: Don't compile demangle-cxx.cpp if not necessary

Arnaldo Carvalho de Melo
2023-05-26T18:27:02Z

Em Wed, Apr 26, 2023 at 10:27:42PM -0700, Ian Rogers escreveu:
> On Mon, Apr 17, 2023 at 12:25 PM Ian Rogers <irogers@google.com> wrote:
> >
> > demangle-cxx.cpp requires a C++ compiler, but feature checks may fail
> > because of the absence of this. Add a CONFIG_CXX_DEMANGLE so that the
> > source isn't built if not supported. Copy libbfd and cplus demangle
> > variants to a weak symbol-elf.c version so they aren't dependent on
> > C++. These variants are only built with the build option
> > BUILD_NONDISTRO=1.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
>
> Testing on arm and noticed we hadn't picked this one up.

Thanks, applied.

- Arnaldo

> Thanks,
> Ian
>
> > ---
> > tools/perf/Makefile.config | 1 +
> > tools/perf/util/Build | 2 +-
> > tools/perf/util/symbol-elf.c | 27 +++++++++++++++++++++++++++
> > 3 files changed, 29 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > index 71442c54c25f..5f0f24b56f50 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -923,6 +923,7 @@ ifndef NO_DEMANGLE
> > EXTLIBS += -lstdc++
> > CFLAGS += -DHAVE_CXA_DEMANGLE_SUPPORT
> > CXXFLAGS += -DHAVE_CXA_DEMANGLE_SUPPORT
> > + $(call detected,CONFIG_CXX_DEMANGLE)
> > endif
> > ifdef BUILD_NONDISTRO
> > ifeq ($(filter -liberty,$(EXTLIBS)),)
> > diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> > index bd18fe5f2719..f9df1df1eec0 100644
> > --- a/tools/perf/util/Build
> > +++ b/tools/perf/util/Build
> > @@ -214,7 +214,7 @@ perf-$(CONFIG_ZSTD) += zstd.o
> >
> > perf-$(CONFIG_LIBCAP) += cap.o
> >
> > -perf-y += demangle-cxx.o
> > +perf-$(CONFIG_CXX_DEMANGLE) += demangle-cxx.o
> > perf-y += demangle-ocaml.o
> > perf-y += demangle-java.o
> > perf-y += demangle-rust.o
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index 35724f6a84fa..cd08bdb9824f 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -31,6 +31,13 @@
> > #include <bfd.h>
> > #endif
> >
> > +#if defined(HAVE_LIBBFD_SUPPORT) || defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
> > +#ifndef DMGL_PARAMS
> > +#define DMGL_PARAMS (1 << 0) /* Include function args */
> > +#define DMGL_ANSI (1 << 1) /* Include const, volatile, etc */
> > +#endif
> > +#endif
> > +
> > #ifndef EM_AARCH64
> > #define EM_AARCH64 183 /* ARM 64 bit */
> > #endif
> > @@ -271,6 +278,26 @@ static bool want_demangle(bool is_kernel_sym)
> > return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
> > }
> >
> > +/*
> > + * Demangle C++ function signature, typically replaced by demangle-cxx.cpp
> > + * version.
> > + */
> > +__weak char *cxx_demangle_sym(const char *str __maybe_unused, bool params __maybe_unused,
> > + bool modifiers __maybe_unused)
> > +{
> > +#ifdef HAVE_LIBBFD_SUPPORT
> > + int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
> > +
> > + return bfd_demangle(NULL, str, flags);
> > +#elif defined(HAVE_CPLUS_DEMANGLE_SUPPORT)
> > + int flags = (params ? DMGL_PARAMS : 0) | (modifiers ? DMGL_ANSI : 0);
> > +
> > + return cplus_demangle(str, flags);
> > +#else
> > + return NULL;
> > +#endif
> > +}
> > +
> > static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
> > {
> > char *demangled = NULL;
> > --
> > 2.40.0.634.g4ca3ef3211-goog
> >

--

- Arnaldo